After three days of temperatures in the upper 90s and high humidity, district officials canceled classes for the rest of the week in 27 buildings that lack much or any air conditioning.

Classes were to resume Tuesday after the Labor Day holiday, and students won't have to make up the time

District spokesman Stan Alleyne told the Minneapolis Star Tribune that the district worried about staff and students becoming ill from the heat.

The heat also closed many Iowa schools. In Eagle Grove, where students were released early all week, Superintendent Jeff Toliver said the window air conditioners in the 1920s-era school simply couldn't keep up with the heat.